# PlanSys2 moves to Kairos and STN

> **Key Architectural Takeaway:** Two big changes are coming to PlanSys2 : a new default planner, Kairos , and a new default plan BT Builder for the executor, STN .

**Published:** 2026-10-13T19:05:07+00:00 
**Source:** ROS Robot Operating System News 
**Category:** robotics-science 
**Canonical URL:** https://fosswire.org/news/plansys2-moves-to-kairos-and-stn.html 

## Executive Summary
Two big changes are coming to PlanSys2 : a new default planner, Kairos , and a new default plan BT Builder for the executor, STN . Kairos is a temporal and numeric PDDL planner developed within the PlanSys2 organization . It does not depend on ROS: it can be used as a C++ library or from the command line. Efficient and robust. On classical, numeric, temporal and robotics benchmarks it solves more problems than LAMA, OPTIC, TFD, POPF and ENHSP under the same limits.

## Architectural & Systems Analysis
From a Linux distribution, deployment reliability, and systems engineering perspective:

- **Dependency Determinism:** Declarative and isolated package trees guarantee reproducible execution across production hosts.
- **Platform Integration:** Tighter alignment with target hardware profiles improves driver interoperability and device stability.
- **Supply Chain Integrity:** Independent package verification and public build infrastructure prevent unauthorized supply-chain regressions.

## Impact on the Open Ecosystem
Strengthens transparent, community-governed distributions against closed software and proprietary lock-in.